Views: 0 Author: Site Editor Publish Time: 2022-10-05 Origin: Site
A large number of practices have proved the remarkable results after the application of modified atmosphere packaging:
- Better product quality and longer shelf life
- Prevent oxidation, spoilage and discoloration
- Improved atmosphere can inhibit bacterial and fungal growth characteristics
- Mechanical protection for fragile products
- Maintains the appearance, smell, flavour and texture of the product thus maintaining its freshness
- Extended shelf life, can replace food transportation methods, greatly reduce transportation costs
2 How to apply MAP?
Due to the different characteristics of the food itself and the different conditions encountered in the transportation and sales of food, the requirements for packaging vary greatly. There are many factors to be considered when using the modified atmosphere packaging technology for food, mainly including the following four elements.
(1) Gas replacement
Use a vacuum pump to extract the air in the packaging bag or box to form a certain degree of vacuum, and then fill it with mixed fresh-keeping gas. After completing the process of gas replacement, the residual oxygen in the package can be less than 1%.
(2) Gas mixing
1 Common mixed gas and characteristics 1) CO2 Carbon dioxide can inhibit most aerobic bacteria and molds. There is no doubt that carbon dioxide is an important gas for gas conditioning in food packaging. Generally speaking, the higher the carbon dioxide concentration, the longer the perishable food will have. However, during the packaging process, fat and water can easily absorb carbon dioxide. If the concentration of carbon dioxide is too high, it will also affect the taste of the food and consume the humidity and concentration of the food (called the vacuum effect). Therefore, it should be carefully considered! How long the shelf life and how much consumption depends on the amount of carbon dioxide. If the purpose of carbon dioxide is to inhibit the growth of bacteria and mold, it is recommended that the concentration be at least 20%. It is also used in perishable foods as a filling gas, similar to carbon dioxide. Nitrogen reduces the vacuum effect and is also a natural part of the air. 3) O2 Oxygen is a very important gas for living organisms, and also supports the deterioration of perishable foods. It is the condition for the growth of aerobic microorganisms. In general, oxygen is not used in MAP, but in some cases, quantitative oxygen yields fairly good results. * It gives perishable food a natural look (a loudness of freshness) . * It allows food to breathe, especially fruit or vegetables. * It can inhibit anaerobic microorganisms in various fish and vegetables.
2 How to mix accurately? The classic gas mixer adopts the principle of double equal pressure and adjusts the proportion of various gases through proportional valves. The gas ratio and accuracy are not affected by changes in the pressure of the gas source and fluctuations in the gas flow, and provide stable and accurate gas supply. With the advancement of science and technology, the KM and MG series gas mixers produced by German WITT company can realize intermittent and continuous simultaneous operation of a single device, and the accuracy of the mixed gas is better than 1%. It has good performance. The mixer is also favored by world-renowned packaging machine manufacturers, and has reached a global strategic partnership with several packaging machine companies such as MULTIVAC, WEBOMATIC, and ILAPAK.
(3) Packaging materials:
1 Commonly used packaging materials are divided into 1) Polyolefin categories: polyethylene (PE) and polypropylene (PP). 2) Vinyl polymer categories: ethylene vinyl acetate copolymer (EVA), polyvinylidene (PVC), polyethylene Vinylidene Chloride Copolymer (PVDC), Ethylene Vinyl Alcohol Copolymer (EVOH),. 3) Polystyrene (PS) 4) Polyamide (PA) 5) Polyester (PET)
2 Attention should be paid to the selection of packaging materials
- The packaging box should be made of high-barrier material, and the boxed film varies according to the characteristics of different products
- The packaging box should have high barrier in terms of moisture permeability, oxygen permeability and light transmission;
- The common characteristics of packaging films are anti-fogging and low light transmittance. Different products with different air permeability should choose different films with different characteristics. For example, the respiration of fruits and vegetables will affect the proportion of mixed gas, and the air permeability of the barrier film must be relied on. to maintain the balance of the gas ratio;
(4) Storage environment:
The best storage environment for modified atmosphere packaging is refrigeration. At present, the temperature of refrigerated food in supermarket refrigerated display cabinets is about 33% higher than 7°C, and about 5% is higher than 13°C. The average temperature of household refrigerators is 10 to 13°C. Obviously, the current cold chain conditions cannot meet the refrigerated temperature and condition requirements of modified atmosphere packaging or vacuum packaged refrigerated food. The recommended refrigeration temperature for many non-breathing refrigerated fresh foods (such as livestock, poultry, and fish) is 0-2 °C, and the recommended refrigeration temperature for many breathing refrigerated fresh foods (such as apples, strawberries, mushrooms) is 0-5 °C. The ambient temperature of storage also directly affects the preservation effect of food.